1. Field of the Invention
The present invention relates to a seatbelt system for restraining and protecting an occupant in an emergency of a vehicle, and particularly to a seatbelt system for automatically fastening webbings for restraining to the occupant after he is seated.
2. Description of the Prior Art
Heretofore, there has been proposed a seatbelt system for automatically fastening a webbing for restraining to an occupant after he is seated. In said seatbelt system, a slider is slidably guided in a guide rail laid on the vehicle body, an outer end of the webbing is secured to said slider, whereby the outer end of the webbing is caused to approach or be separated from an occupant's seat, thereby bringing the webbing into contact with or separating same from the seated occupant.
In said automatically fastening type seatbelt system, it is necessary that said slider should be reliably engaged with the vehicle body at an automatically fastening position to which said slider reaches after moving in a direction of the occupant's seat along the guide rail. More particularly, in an emergency of the vehicle, a high tension is generated in the webbing due to a colliding inertial force of the occupant. Hence, it is necessary to make the vehicle body reliably support the tension, so that the occupant can be reliably restrained by the webbing.
From this reason, heretofore, there has been proposed means of preventing the slider from moving by use of a locking device such as a solenoid driven by an electric power source of the vehicle when the slider reaches the automatically fastening position. However, such means has been complicated in construction and tended to cause unexpected failures due to interruption of power supply in a collision of the vehicle.